Abstract : The Voice-Controlled Disappearing Audio Delay Line automatically (by voice only) controls the operation of a half-duplex voice scrambler which uses a preamble. In conjunction with a control circuit, it keys the scrambler when a voice signal appears at the input, stores the signal as the preamble is being transmitted, feeds the signal into the scrambler at the end of the preamble transmission, eliminates the delay at the scrambler input as the message continues, and unkeys the scrambler when an end-of-message is unrecognized. (Author)